This is TRISMUS. This is a lock jaw syndrome
. u need to check with a oral surgeon with appropriate x-rays whether it is due to some impacted wisdom tooth
. or any other dental issue. Can also be neuralgia. I think giving a cold pack will not help as neuralgia will increase in cold conditions. Also rule out middle ear infection
by ENT. Usually ur ear would be blocked if u have chronic cold and severe sinusitis
. I would advice Vit B&C supplements and hot inhalalations.